Most studies on workplace bullying have adopted a between-person approach, neglecting the potential within-individual fluctuations in the experience of bullying behaviors. However, investigating such fluctuations may prove useful for uncovering processes and mechanisms associated with bullying and its antecedents and consequences as they unfold over time. In the present study, based on recent discoveries on traumatic experiences and posttraumatic stress (PTS), we hypothesized that even short-term exposure to bullying behaviors-such as the exposure that characterizes an individual when the time window considered is a working week-may already have a substantial psychological impact at the within-individual level, as indicated by the experience of PTS symptoms. Additionally, we hypothesized that the development of workplace phobia may act as a mechanism linking the exposure to bullying behaviors during the week and the reported PTS symptomatology, and that person-level vulnerability factors to PTS (e.g., a recent trauma and female gender) accentuate the within-individual relationships. We tested the proposed hypotheses on a sample of 158 workers that were followed for 6 consecutive working weeks for a total of 860 observations. In line with other recent within-individual investigations, we found that exposure to bullying behaviors shows substantial week-level fluctuations. We also found overall support for the hypotheses, including evidence of a within-level lagged impact of bullying behaviors on workplace phobia, suggesting that even nonpersistent exposure to such behaviors is related to potentially nonignorable psychological suffering and PTS symptoms. (PsycInfo Database Record (c) 2024 APA, all rights reserved).